Method of and means for electroplating



Aug. 12, 1930. w. s. MURRAY 1,772,840

METHOD 0F AND MEANS FOR ELECTROPLATING Original Filed March 8, 1924 2Sheets-Sheet l 1939. w. s. MURRAY 1,772,840

METHOD OF AND MEANS FOR ELEGTROPLATING Original Filed March 8, 1924 2Sheets-Sheet 2 gmvamboz Patented Aug. 12, 1930 NITED STATES PATENT IoFFica WHQLIAM S. MURRAY, OF UTICA, NEW YORK, ASSIG-NOR TO ONEIDACOMMUNITY,

LIMITED, OF ONEIDA, NEW YORK, A CORPORATION OI NEW YORK METHOD OF ANDMEANS FOR ELECTROPLATIN G Application filed March 8, 1924, Serial No.697,708. Renewed July 28, 1927.

This invention relates to improvements in methods of and means forelectro-depositing metals.

Heretofore the electro-deposition of metals upon the bases or objects tobe plated has been accomplished by the use of a direct current of lowvoltage passing through the plating solution and maintained at aconstant current density or amperage during the period ofelectro-deposition.

According to the present invention the current density is changed atregular, redetermined intervals, according to the ob ect to be attained,which may be a desired color or density in the plating, greater speed inplating than is possible with the direct current of uniform densityheretofore used, or the plating successively of a plurality of differentmetals.

The invention is of special importance for the plating of a plurality ofmetals and for this reason it will. be described in detail in thatconnection although it is to be understood that it is not to be solimited.

The best potential for electrodepositing various metals varies accordingto the metal in question. The purpose of the present embodiment is to sovary the external resistance in the plating circuit that the bestpotential and therefore the best current density for depositing thesemetals from the same solution may be obtained.

In the accompanying drawings- Figure 1 is a plan view and Figure 2 aside elevation of a preferred form of mechanism embodying and forpracticing the improvements of the present invention;

Figure 3 is a vertical section thereof on the line 3-3 of Figure 1, andFigures 4, 5, 6 and 7 are details of certain parts of said mechanism,which will be hereinafter fully described; and

Figure 8 is a diagrammatic view illustrating the way in which saidmechanism is used for obtaining the results before referred to.

The mechanism shown includes a frame 1 having bearings 2 in which isjournaled a enlargement and the ends of the shaft with two sets of discs6-7 loosely mounted on the shaft so that they may be rotarily adjustedthereon and then locked in such adjusted position by means of nuts 8which when screwed inwardly along the shaft force the discs towards theenlargement 5 which acts as an abutment for the discs and, with the nuts8, securely locks them in their adjusted position.

In front of each of these two sets of discs 6"i' there is mounted abrush holder 9-9 and in said brush holder there is mounted a brush1()1() which is pushed towards the discs by springs 11, its movement inits direction, however, being limited by stops 12. These two brushes 10are connected by wires 1314, respectively, and wire 15 with one terminalof a generator 16, the one terminal which is connected by a wire 17 withthe cathode holder or terminal 18 of an electrolytic plating bath 19.

Wires 1314 include resistances 20 21 of different values, the resistance20 being weaker than the resistance 21.

On what may be termed the rear side of the machine, frame, there ismounted a second brush holder 22 and in this brush holder is mounted abrush 23 which is pressed outwardly by springs 24 into engagement withthe enlargement 5 of shaft 3. This brush is connected by wire 25 withthe anode holders or terminals 26 of the bath 19. These terminals are soarranged relatively to the cathode terminal 18, that the currents willflow from the anodes in different directions to the cathode.

The discs 67 have radially projecting portions 6 the surfaces of whichare concentric with the axis of shaft 3.

The extent to which these said metal contacts project from shaft 3 issuch'that as said shaft rotates they will contact with brushes 10 and10, respectively, and thereb close the circuit from generator 16 throughath 19 by way of resistance20 and brush 10, when the said metal contacts6 of discs 6 are in engagement with said brush 10, or by way ofresistance 21 and brush 10 when the segmental It will be understood thatthe variation in the relative strengths of these two resistances willresult in corresponding changes in potentials and thereby densities ofthe currents through the bath 19. In the present case, the resistance 20is weaker than the resistance 21 .with the result that the density orvalue of the current passing thence through the bath 19 will be greaterwhen the current passes through than the current passing throughresistance 21 to the bath.

The discs of each set are, as before stated, relatively adjustablecircumferentially on the shaft 3 so that their segmental contacts 6 or 7a may be ali ed with each other axially on the shaft or e arrangedspirally, or one in advance of another, around the shaft, as shown forexample in the drawings. When so aligned, the duration of contactbetween segmental contacts 6 or 7, as the case current traversing thebath 1%) ma may be, will continue for only a short time, namely for 712" in the case of discs 6 and 36 in the case of discs 7.

,When, however, these discs are adjusted withwtheir segmental contactsspirally arranged around theshaft 3 the duration of contact may in thecase of discs 6 be con tinned, without interruption, for 72, and in thecase of discs 7, for 360.

It will thus be seen that with these two sets of discsand the twobrushes 10-40, the

be pulsated to any desired degree, accord1ng to the character of theresistances, as 202l, employed between the, generator and the brushes10-40. This will depend upon the character of plating desired to beproduced by the bath 19.

What is claimed is:

1. The combination with an electroplating circuit including as a cathodethe article to be. plated, of means for periodically-decreasing andincreasing from one uniform value to another uniform value the densityof the current passing through said cathode at reg ularl controlledintervals while maintaining t e same sign of polarity of said current.

4. The combination with an electroplating circuit including as a cathodethe article to be plated, of means for subjecting the plating circuit tothe action of a pulsatory. all

waysuni-directional current which changes from one uniform value toanother umform value, and adjusting the duration and amplitude of theindividual pulsations and the duration of the intervals betweenpulsations to give the desired coating on the article.

5. In a process of electroplating in which the article to be plated isincluded as a cathode in the plating circuit, the method of controllingthe nature of the coating deposited on the article, which consists inperiodically decreasing and increasing from one uniform value to anotheruniform value the density of the current passing through said cathode atregularly controlled intervalswhile maintaining said current alwaysunidirectional. 6.. In a process of electroplating in which the articleto be plated is included as a cathode in the plating circuit, the methodof controlling the nature of the coating deposited on the article, whichconsists in changing from one uniform value to another uniform value thedensity of the current passin through said cathode at regularlycontrolle intervals while maintaining said current alwaysuni-directional. n. 7. In a process of electroplating in whic thearticle to be plated is included as a cathode in the plating circuit,the method of controlling the nature of the coating deposited on thearticle, which com rises periodically and alternately flowing e ectriccurrents of different uniform densities to the cathode from anodeslocated in different directions from the cathode, said currents beingunidirectional at all times and flowing in the same direction relativeto the cathode.

8. In a process of electroplating in which the article to be plated isincluded as a cathode in the plating circuit, the method of controllingthe nature of the coating deposited on the article, which comprisessubjecting the plating circuit to the action of a pulsa tory, alwaysuni-directional current which changes from one uniform value to anotheruniform value, and adjustin the duration and amplitude of the indivi ualpulsations and the duration of the intervals between pulsations to givethe desired coating on the article. I 1

In'testimony whereof, I have hereunto set my hand. N

WILLIAM S. MURRAY. I

